We report herein on a Japanese patient with Ancylostoma ceylanicum infection on returning from Papua New Guinea who was diagnosed by molecular identification of the parasite eggs. The patient was a 26-year-old male who stayed at Lorengau city, Manus Province, Papua New Guinea for 2 years. He was providing guidance about agricultural technology and doing his work barefoot with local residents. After returning from Papua New Guinea, hookworm eggs were detected during a feacal examination as part of a health checkup and he was referred to our hospital for further examination and treatment. He had not had any health problem such as dermatitis, fever or respiratory or abdominal symptoms during his stay in Papua New Guinea. On admission to our hospital, the laboratory data revealed a normal WBC count with hypereosinophilia (20.9%). Feacal examination with the Kato cellophane thick smear technique showed 220 eggs/g feces of hookworm eggs. For species identification, DNA extracted from eggs obtained by the floatation method with saturated sodium chloride solution were subjected to a PCR assay specific for the mitochondrial cytochrome c oxidase subunit 1 (Cox1), ribosomal internal transcribed spacers (ITS) -1 and ITS-2 genes. The cox1 region was very close to, and ITS-1/ITS-2 region were shown to have a 100% sequence identity with the A. ceylanicum sequence. The patient was treated with a single dose of pyrantel pamoate (10 mg/kg). No eggs were found in further feacal examinations and the eosinophilia improved to a normal level at 4 weeks after the treatment.

Eosinophilia in returning travelers is one of the clues for suspicious helminth infections even though the patients are asymptomatic. Physicians should recognize the possibilities of helminth infection including hookworm and proceed to appropriate parasitological examinations considering the countries the travelers' have visited, their living environment, their activities while there, and the endemic parasite species.

[ Kansenshogaku Zasshi 91: 759-763, 2017 ]

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